Free-surface fluctuations in hydraulic jumps: Experimental observations

Murzyn, Frederic and Chanson, Hubert (2009-10) Free-surface fluctuations in hydraulic jumps: Experimental observations. Experimental Thermal and Fluid Science, 33 7: 1055-1064.

Document type: Journal Article
Sub-type: Article
Collections: 2010 Higher Education Research Data Collection
School of Civil Engineering Publications

Author(s) Murzyn, Frederic
Chanson, Hubert
Title Free-surface fluctuations in hydraulic jumps: Experimental observations
Journal name Experimental Thermal and Fluid Science    (ERA Rank A)
Publication date 2009-10
Sub-type Article
Year available 2009
Volume number 33
Issue number 7
ISSN 0894-1777
Start page 1055
End page 1064
Total pages 10
Editor(s) I Kennedy
L A Kennedy
Place of publication New York, United States
Publisher Elsevier
Collection year 2010
Language eng
Subject 090509 Water Resources Engineering
C1
970109 Expanding Knowledge in Engineering
Abstract A hydraulic jump is the rapid and sudden transition from a high-velocity supercritical open channel flow to a subcritical flow. It is characterised by the dynamic interactions of the large-scale eddies with the free-surface. New series of experimental measurements were conducted in hydraulic jumps with Froude numbers between 3.1 and 8.5 to investigate these interactions. The dynamic free surface measurements were performed with a non-intrusive technique while the two-phase flow properties were recorded with a phase-detection probe. The shape of the mean free surface profile was well defined and the turbulent fluctuation profiles highlighted a distinct peak of turbulent intensity in the first part of the jump roller, with free-surface fluctuation levels increasing with increasing Froude number. The dominant free-surface fluctuation frequencies were typically between 1 and 4 Hz. A comparison between the acoustic sensor signals and conductivity probe data suggested that the air-water "free-surface" detected by the acoustic sensor corresponded to about the boundary between the turbulent shear layer and the upper free-surface layer. Simultaneous measurements of free surface and bubbly flow fluctuations for Fr = 5.1 indicated that the frequency ranges of both sensors were similar (F < 5 Hz) whatever the position downstream of the toe. The present results highlighted that the dynamic free-surface measurements can be conducted successfully using acoustic displacement meters, and the time-averaged depth measurements was a physical measure of the free-surface location in hydraulic jumps.
Keyword(s) Hydraulic jumps
Free-surface fluctuations
Characteristic frequency
Turbulent shear flow
Air bubble entrainment
Roller length
Experimental techniques
Non-intrusive measurements
Q-Index Code C1
 
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Created: Fri, 14 Aug 2009, 00:01:20 EST by Hubert Chanson on behalf of School of Civil Engineering  -  Detailed History